Stabilizing vinylidene chloride



Patented June 21, 1938 V UNITED STATES OFFiCE STABILIZING VINYLIDENECHLORIDE Michigan No Drawing.

Application April 26, 1937,

Serial No. 138,934

5 Claims.

This invention relates to methods of stabilizing vinylidene chloride,HzC=CClz,'and to the improved composition thereby obtained.

When vinylidene chloride is exposed to the action of air and light, agradual polymerization takes place with the formation of resinousproducts. The formation of such polymeric compounds is desirable in thepreparation of plastics, but it is necessary that the material bestabilized, at least temporarily, against such polymerization, so thatit can be stored for a period of time following its preparation, andprior to its use in resin formation. It is, therefore, among the objectsof this invention to provide a process for inhibiting the polymerizationof vinylidene chloride. A further object of the invention is to providea relatively stable monomeric vinylidene chloride. Another object of theinvention is to provide a stabilized vinylidene chloride compositionfrom which the stabilizing agent can be readily removed when desired.

We have discovered that vinylidene chloride can be stabilized againstthe action of air and light by incorporating therewith one or acombination of certain derivatives of diphenylamine, and, furthermore,that these stabilizing agents can again be readily separated from thevinylidene chloride to render the same capable of polymerization.

The concentration of stabilizing agent to be employed in monomericvinylidene chloride may be varied, depending upon the length of time forwhich is desired to stabilize the compound and upon the effectiveness ofthe particular agent employed. We have found that an amount ofstabilizing agent equivalent to 10 per cent or less of the weight ofvinylidene chloride is ordinarily sufficient to maintain the vinylidenechloride in In a preferred method of carrying out our invention, a smallamount of one of the stabilizing agents mentioned above, suitably oneper cent, or less, based on the weight of vinylidene chloride, is addedto freshly distilled monomeric vinylidene chloride, which may then bestored in a container. When it is desired to utilize the stabilizedvinylidene chloride in polymerization processes, the stabilizing agentmay be readily and completely removed from the solution by distillingoff the lower boiling vinylidene chloride. The stabilizing agent is leftin the still as a residue after the distillation, and is adapted to bere-employed for the stabilization of further amounts of vinylidenechloride. The vinylidene chloride removed from the stabilizer bydistillation is found to polymerize readily when exposed to light, air,elevated temperature, or other of the customary catalysts oraccelerators for the polymerization.

The following example serves to illustrate the practice of ourinvention:

99.5 grams of vinylidene chloride were placed in each of 7 flasks. To 6of the samples there was added 0.5 gram of one of the new stabilizingagents, namely, 4.4-dihydroxy-diphenylamine, 4.4 dimethoxydiphenylamine, N nitroso-diphenylamine, i-phenyl-amino-diphenylamine, 4-benzene-sulphon-amino-diphenylamine, and the material produced byreacting acetone and diphenylamine. The samples were allowed to stand atroom temperature and in contact with the air for a period of 2 weeks, atthe end of which time no polymerization or oxidation of the vinylidenechloride could be detected. In each instance, the vinylidene chloridedistilled readily from the stabilizing agent and was thereafter readilypolymerized. The untreated sample of freshly disstilled vinylidenechloride was found to have polymerized substantially completely afterstanding for 24 hours at room temperature and in contact with air. Afterhaving stood for only 5-6 hours, this untreated sample displayedevidence of polymerization and of oxidation, there being readilydetected the odor of phosgene, one of the normal oxidation products ofvinylidene chloride. Attempts to recover the vinylidene chloride fromthe polymerized untreated sample thereof resulted only in furtheroxidation and decomposition.

Other modes of applying the principle of our invention may be employedinstead of those explained, change being made as regards the materialsemployed, provided the step or steps or the products recited in thefollowing claims be thereby carried out or obtained.

phenylamine, N-nitroso-diphenylamine, 4-phenylamino-diphenylamine,4-benzene-sulphon-aminodiphenylamine, and acetone-diphenylamine reactionproduct.

3. Vinylidene chloride stabilized with 4.4'-di 5 hydroxy-diphenyiamine.

4. Vinyiidene chloride stabilized with 4-phenylamino-diphenylamine.

5. Vinylidene chloride stabilized with4-benzene-suiphon-amino-diphenylamine.. 10 EDGAR C. BRITTON.

WALTER J. LE FEVRE.

